The propagation of radially polarized partially coherent beams in uniaxial crystals orthogonal to the optical axis is investigated. The analytical formulae for the elements of the cross-spectral density matrix of radially polarized partially coherent beams propagating through uniaxial crystals orthogonal to the optical axis are derived. The effect of initial coherence and ratio of extraordinary and ordinary refractive indices on the intensity and effective beam widths is illustrated analytically and numerically. The results show that the propagation properties of radially polarized partially coherent beams in uniaxial crystals orthogonal to the optical axis are closely related to the initial coherence and the ratio of extraordinary and ordinary refractive indices.

This paper presents a 3D numerical model of magnetoelectric sensors based on the finite element method. It is obtained using the association of magnetoelastic and piezoelectric behaviour laws. The 3D finite element formulation is evaluated on a bi-layer beam, combining magnetostrictive and piezoelectric materials, submitted to magnetic fields. These results are compared to the ones obtained with a validated 2D finite element model. At last, a cylindrical magnetoelectric sensor, which can not be modelled with a 2D analysis, is evaluated.

This work deals with the eddy current nondestructive testing of carbon fiber reinforced polymer composites (CFRPs), and the development of rapid numerical models for the simulation of the interaction between the electromagnetic field and complex structures. We show qualitatively the possibility of characterizing the CFRPs by using a rotating eddy current sensor. We make use of a numerical model which we have developed in a previous work for eddy current computation in CFRPs. This model is completed in this work to account for the impedance variation of the rotating eddy current sensor, used to determine the anisotropy factor and the fiber orientation in each ply of a layered CFRP plate.

The effect of (0.5–3.5) wt.% Ag additions on microstructure, melting, corrosion and mechanical properties of Sn-9Zn eutectic lead-free solder alloy has been studied and analyzed. The study included X-ray diffraction and scanning electron microscopy (SEM) to identify the microstructure of these alloys. The results showed that, continuous additions of Ag caused formation of Ag-Zn and Ag-Sn compounds which led to decrease the precipitations of Zn in Sn-matrix. These compounds led to increase the melting point of the alloys, which confirmed by the formation of small endothermic peaks in the higher temperature range followed the main peak of the DTA curves. Also, the DTA measurements confirmed that the alloy of composition Sn-9Zn-3.5Ag is the ternary eutectic alloy. Vicker's micro-hardness number of Sn-9Zn alloy increases with small additions of 0.5 and 1 wt.% Ag. Furthermore, it decreases to lower values with further increase of Ag content. Also, micro-creep behaviour, creep rate and corrosion behaviour of the Sn-9Zn-Ag alloys have been measured at room temperature.

In this paper, we present an alternative method to Sommerfeld integrals for the calculation of a point source radiation in a multilayered background, based on the method of auxiliary sources, also called fictitious sources method. The method lies upon the decomposition of reflected and transmitted fields on a basis of secondary sources, which amplitudes are determined by applying boundary conditions at each multilayer interface, solving an over-determined system of equations. We present a generalization of the classical FSM to open stratified domains, with arbitrary number of layers and arbitrary position of the point source in the multilayer. Two and three dimensional formalisms are proposed, and compared to exact Sommerfeld formulation. Computation time reduction factors as high as 100 are obtained for 2D problems. Moreover, this method enables the study of non-flat interfaces, which is not possible with Sommerfeld approach. This method can be used for example in order to determine radiation efficiency of emitting devices, or it can be integrated in discrete source type electromagnetic methods for calculation of scattering by a complex target.

Laser propulsion in a water environment is influenced by oscillating features of a laser-induced bubble. In our study an optical beam deflection method is used to investigate dynamics of laser-induced semispherical cavitation bubbles near three different interfaces: the rigid boundary (water-solid interface), the free surface (water-air interface) and the liquid-liquid interface (water-soybean oil interface), and in the bulk. The maximum radius of the first bubble oscillation R max1 was widened and the collapse time T 1 is prolonged in the case of the rigid boundary. R max1 is diminished and T 1 is shortened in the case of the free surface and the water-oil interface, among which the latter makes R max1 even smaller. In order to get the maximum propelling force in different distances near different medium interfaces, different pulse energy of the laser is used. The bubble moves toward the rigid boundary and moves away from the free surface during its oscillations. This will change the application point of the propelling force on the object, and cause a change in the propelling direction of the object.

In this work, an original procedure, based on the finite element method, is presented for the design of a Levitron©, a device made of permanent magnets and relying on stable gyroscopic magnetic levitation, using secondhand components. A perturbation force analysis is performed on finite element models of available magnets in order to derive the locus of stable equilibrium, as well as the top mass, for a given configuration of the magnets. We investigate three methods for the estimation of forces from finite element computations, two of them based on the Virtual Work principle, and one performing numerical integration of the classical expression of forces between magnets. Results are employed to realize a Levitron© in laboratory, and are shown to be in better agreement with experience than those from a simple analytical model available in the literature.

The discrete kinetic model is used to study the propagation ofsound waves in system of hard-disk-like rotating gases. Theanomalous (negative) attenuation or amplification which ispossibly due to the binary collision of a dilute-enough rotatingdisk system (each with opposite-sign rotating direction or angularmomenta but the total (net) angular momenta is zero) ormicroreversibility might arise from the implicit balance of theangular momentum during encounter. Our results might give usefulidea to the instrumentation set-up of possible acceleration ofcosmic rays passing through this kind of channel and direct orinverse cascades in two-dimensional rotating gases ofastrophysical problems.

A mainly orthogonal and locally barycentric dual mesh is used to improve the performances of a generalized finite difference method. A criterium is proposed to choose between an orthogonal and a barycentric construction for the dual mesh taking into account stability considerations for an explicit time scheme. The construction of the constitutive matrix is performed using either the microcell or the Galerkin method. The proposed method is shown to considerably reduce the computational cost in the assembly process and the resolution compared to methods using completely barycentric dual meshes.

The band structure of Li2B4O7(100) and Li2B4O7(110) was experimentally determined using a combination of angle-resolved photoemission and angle-resolved inverse photoemission spectroscopies. The experimental band gap depends on crystallographic direction but exceeds 8.8 eV, while the bulk band gap is believed to be in the vicinity of 9.8 eV, in qualitative agreement with expectations. The occupied bulk band structure indicates relatively large values for the hole mass; with the hole mass as significantly larger than that of the electron mass derived from the unoccupied band structure. The Li2B4O7(110) surface is characterized by a very light mass image potential state and a surface state that falls within the band gap of the projected bulk band structure.

The modeling and design of eddy currents sensors for non-destructive testing applications, generally, requires numerical methods. Among these methods, the finite element method is one of the most used. Indeed, it presents a great capability to treat a large variety of configurations. However, in the study of eddy current testing problems, the existence of structures that have a geometrical dimension smaller than the others (thin air gaps, coatings...) will lead to difficulties related to the meshing process. The introduction of particular elements such as shell elements allows to simplify the modeling of these problems. In this paper, the shell elements are used in two different 2D axisymmetric formulations, the electric formulation a* and the magnetic formulation t-ϕ in order to simulate the behaviour of the electromagnetic fields. The results obtained with the two formulations are compared with analytical solutions.

A perturbation method for the A-χ geometric formulation to solve eddy-current problems is introduced. The proposed formulation is applied to the feasibility design of a non-destructive evaluation device suitable to detect “long” longitudinal flaws in hot steel bars.

We present here an original application linking an electrochemical domain and the computational aspect of electromagnetic fields to make a corrosion diagnosis of a protected underwater steel structure. After a defined operating time, it is mandatory to check an underwater steel structure. This control may happen too early, if the protection has not been damaged; but it may happen too late, if some particularly bad environmental conditions have already damaged the structure. Moreover, current examination techniques require immobilizing the structure for a long time: they may be complicated to dry (pipe lines or tanks) or to place in dry docks for vessels. The efficiency of these techniques could be improved. The purpose of this paper is to replace this checking/examination by a series of close electrical measurements in the electrolyte which provides a corrosion diagnosis of the structure. This also allows computing the electric and magnetic fields caused by this phenomenon everywhere in the electrolyte. The new method introduced ensures a great time-saving but also an accuracy never reached before.

Following ICNIRP Guidelines of 1998, European Parliament in 2004 has stated the reference levels for workers exposure to electromagnetic fields. In low frequency regime, due to the nature of the basic mechanism of short term interaction, the exposure limits are based on the values of induced eddy currents inside human body, thus electromagnetic simulation is an important tool for the assessment of electromagnetic field exposure. This paper presents a method for computing eddy currents inside human body and applies the method to the evaluation of eddy currents induced by a resistance spot welding system. A comparison between results obtained with two different models of human body and with different discretization levels is performed and results are discussed.